What is Membrane Potential?

Membrane Potential refers to the potential difference between two solutions separated by a membrane. Generally refers to the electrical phenomenon accompanying the cell's life process, the potential difference existing on both sides of the cell membrane. Membrane potential plays an important role in the process of nerve cell communication. In 1791, Italian anatomist L. Galvani accidentally discovered that if the muscles of a frog's legs were placed on an iron plate and the frog's spinal cord was hooked with a copper hook, the muscles would occur when the copper hook contacted the iron plate. The contraction, he attributed this phenomenon to animal electricity.

Chinese name: Membrane potential

English name: Membrane Potential

Definition 1: Due to the different concentrations on both sides of the membrane

In 1791, Italian anatomist L. Galvani accidentally discovered that if the muscle of a frog's leg is placed on an iron plate and the copper hook is used to hook the frog's

The uneven distribution and selective transmembrane movement of some key ions inside and outside the cell are the basis for forming membrane potentials. The transmembrane permeation of each ion is relatively independent. This phenomenon is also called the principle of independence of ion movement. ^[2]

According to the concept of general physiology, a membrane potential can be generated by forming a difference in ion concentration on both sides of a biofilm. The potential difference between two sides of a quiet cell is called a transmembrane resting potential, also known as a resting po -tential) and membrane potential. When excited cells are stimulated, the most critical and essential common change is a transient potential fluctuation based on the cell's resting potential, which is the acting poteniial. However, the conduction of the action potential on the membrane is different from the propagation of waves in the medium. The energy of the waves comes from the vibration source, so the amplitude of the vibration will decrease with the increase of the propagation distance, and eventually disappear. However, the magnitude of the action potential in any place on the membrane is mainly determined by the distribution of ions inside and outside the membrane. A large number of experimental studies have confirmed that only the vestibular membrane, inner hair cells, and outer hair cells have membranes in the cochlea with poor ion concentration ^[4]

At rest, the neuronal cell membrane makes the potential inside the cell "negative" than the potential outside the cell. ; Sometimes the potential inside the cell membrane can be more than 60 mV lower than the potential outside the cell membrane (hyperpolarization). At the resting potential, neurons can reversely inject low-level potassium ions into the cells through sodium-potassium-ATPase, etc., and concentrate them inside the cells. The cell membrane potential at rest is the result of the balance of potassium, sodium, calcium, and chloride ions inside and outside the cell membrane. According to the formula, the intracellular potential is lower than the extracellular potential by 58 mV (-58 mV). When the cell's resting membrane potential is -58 mV, it can trigger the opening of sodium channels in the cell membrane, rapid inflow of sodium ions, depolarization of the cell membrane, and nerve cell excitement. When the cell membrane resting potential is negative -58 mV, it can trigger the opening of potassium ion channels in the cell membrane, persistent efflux of potassium ions, hyperpolarization of the cell membrane, and inhibition of nerve cells. The threshold of neuron-induced action potential is -44 to -55 mV. The rapid influx period of sodium ions is often the absolute refractory period, which can prevent the recurrence of action potential. At the action potential, only a small amount of potassium and sodium ions flow, which will not significantly change the ion concentration inside and outside the cell. The resting membrane potential of neuronal cells is the equilibrium potential of a variety of ions, and all ions can diffuse along the concentration difference, and the diffusion is more pronounced at the action potential ^[5] .